Even major fluctuations. Not talking about the quality here (but the received quality is identical to what is being sent), but just think about Netflix & Co, Imagine if they had to maintain an "ideal network, with no packet loss and constant ping" to your device or otherwise audio and video would be out of sync?

There are protocols that shuffle more or less raw audio streams over the network (Dante for example). In that case yes, you do things to make sure the variables are within a certain range by (usually) segregating the traffic etc, but even then if the timing is off the playback will stop until the stream is reestablished properly. Theoretically it's the same as with any other media stream, just much more sensitive to fluctuations as it is real time (i.e. delay so low you are unable to hear it).